OICC Press Journal of Nanostructure in Chemistry 2193-8865 9 3 (September 2019) 2019 08 10 Biosynthesis of Ag and Fe nanoparticles using Erodium cicutarium; study, optimization, and modeling of the antibacterial properties using response surface methodology 10.1007/s40097-019-0311-z EN Nahid Maghsoudy Department of Chemistry, Science and Research Branch, Islamic Azad University, Tehran, IR Parviz Aberoomand Azar Department of Chemistry, Science and Research Branch, Islamic Azad University, Tehran, IR Mohammad Saber Tehrani Department of Chemistry, Science and Research Branch, Islamic Azad University, Tehran, IR Syed Waqif Husain Department of Chemistry, Science and Research Branch, Islamic Azad University, Tehran, IR Kambiz Larijani Department of Chemistry, Science and Research Branch, Islamic Azad University, Tehran, IR Journal Article 2019 08 10 Abstract The present study deals with the preparation of silver (Ag) and iron (Fe) nanoparticles, extracted from AgNO 3 and FeSO 4 ·7H 2 O solutions, respectively. For this, the aqueous extract of Erodium cicutarium was used. The Ag and Fe nanoparticles were characterized by several techniques such as X-ray diffraction (XRD), field emission scanning electron microscope (FE-SEM), energy dispersive X-ray (EDX) spectrometer, UV–visible, and Fourier transform infrared (FTIR) spectroscopy. FE-SEM images showed that the Ag and Fe particles had nearly spherical morphology with diameters less than 100 nm. Low amounts of impurity and different chemicals in the prepared nanoparticles were confirmed by EDX spectrometers. Furthermore, different functional groups in the nanoparticles were indicated using FTIR spectrum. Antibacterial activity of the Ag and Fe nanoparticles was evaluated by minimum inhibitory concentration (MIC) for E. coli and S. aureus bacteria. Two parameters such as the concentration of Ag and Fe nanoparticles ( X 1 ) and pH ( X 2 ) were modeled by the use of the response surface methodology (RSM). These experiments were carried out as a central composite design (CCD) consisting of 13 experiments. The results showed that the concentration of Ag and Fe nanoparticles had a better effect on antibacterial activity. Under optimal conditions—with concentrations of Ag and Fe nanoparticles at 399.53 and 397.38 (μg/mL) and pH values of 8.20 and 8.39, respectively—the bacterial growth inhibition halo was found to have the highest diameter. Graphic abstract